1. Field of the Invention
This invention relates to coaxial cable connectors.
2. Introduction to the Invention
With the continuing increase in the supply and demand for programming and services provided via cable television and the like, plus the improved quality and additional features available with digital technology, the bandwidth requirements for such cable systems has increased greatly. Whereas, in the past, such systems have operated satisfactorily with signals in the range of up to perhaps 750 MHz, demands imposed on new systems require signals of 1 GHz or more, and plans for future systems will require signals up to 1.8 to 2.2 GHz or even 3 GHz. Moreover, in addition to carrying broadband signals, as new services are offered via coaxial cable, systems providing such new services are often required to carry power to amplifiers, repeaters and other equipment in the cable transmission system, and/or to subscriber equipment to supplement, back-up or substitute for local utility power.
A connector commonly used in coaxial cable systems is known as the F-connector. The F-connector is typically found on cables and devices from the cable tap at the distribution cable to the subscriber equipment. A male F-connector is typically used to terminate a coaxial cable. A female F-connector may be used to join two cables together or to connect a cable to a device. Because F-connectors are used in such large quantities, it has been necessary to develop F-connectors which are easily assembled and inexpensive. As a result, while adequate for use in past systems, such connectors are typically not adequate to carry the broad spectrum of signals and power required in the emerging cable systems.
One reason prior art F-connectors are not suitable for use in new broadband systems is that such F-connectors do not match the characteristic impedance of the coaxial cables to which they connect, thereby degrading the signals carried on the coaxial cables. One such F-connector, disclosed in U.S. Pat. No. 5,096,444 ("the U.S. Pat. No. '444"), exemplifies the problem. The F-connector disclosed in the U.S. Pat. No. '444 comprises seizing contacts (56 and 58) which are similar to other prior art seizing contacts (16, 22) illustrated in the U.S. Pat. No. '444. Seizing contacts such as those depicted in the U.S. Pat. No. '444 are commonly used in prior art F-connectors.
Other variations of connector approaches, not necessarily limited to F-connectors, are disclosed, for example, in U.S. Pat. Nos. 4,734,064 (the U.S. Pat. No. '064) and 5,456,611 (the U.S. Pat. No. '611). The U.S. Pat. No. '064 discloses an electrical socket which comprises cantilever spring tines (18) which terminate in a convex cross section at their free ends. The spring tines expand as they guide an inserted pin during engagement. The U.S. Pat. No. '611 discloses a circular sleeve comprising a plurality of spaced-apart, axially oriented tines (30).
The disclosures of U.S. Pat. Nos. 4,734,064, 5,096,444 and 5,456,611 are incorporated herein by reference for all purposes.
However, while designed to provide physical and electrical contact with a male connector contact inserted therein, such seizing contacts, tines, and the like, and the connector assemblies in which they reside, are not necessarily designed to properly match the characteristic impedance of the coaxial cables. Such arrangements may be deficient in several respects. The radius of the contact mechanism varies along the length of the mechanism, thereby causing the characteristic impedance of the connector to likewise vary along its length. Next, the outer radius of the contact mechanism does not bear a proper relationship with the inner radius of the connector housing. In addition, when a mating pin or wire is inserted into the contact mechanism, the contact mechanism expands to accept the inserted pin or wire, thereby changing the radius of the contact mechanism, and the amount of such change will depend on the diameter of the inserted pin or wire.
Prior art coaxial cable connectors which are suitable for carrying signals at frequencies of 1 GHz or more are very expensive, as they are typically constructed to fine tolerances thereby requiring significant handling, machining and other such expensive operations. Therefore, such connectors are often available primarily for use in the laboratory in conjunction with expensive equipment, but are normally too expensive to be deployed in the field. Because such connectors are constructed to fine tolerances, such connectors can normally be mated only with male connectors comprising wires, pins or other substrates of a specific size (length and/or diameter) and shape, and often such mating substrates likewise must be machined to fine tolerances. Moreover, the depth to which a mating male substrate can penetrate a female connector is a function not only of the length of the male substrate but also other characteristics of the connectors such as the number of threads on the respective connector housings. Since the number of threads on the housings of male connectors produced by different manufacturers may vary, the female connectors must be capable of accommodating such variations.
It is therefore desirable to provide an inexpensive coaxial cable connector which is capable of carrying signals from low frequency power up to and including telecommunications signals in the range of 1 GHz or more. It is further desirable that such connectors be suitable for use with mating connectors comprising wires, pins and other substrates, including clipped wires, and in which such substrates may be of various lengths and/or diameters, and need not be machined to fine tolerances. It is still further desirable that there be such connectors which are suitable for use in joining two cables together and such connectors which are suitable for connecting a cable to a device.